How the works An explanation for a layperson

by Darob Malek-Madani

he internet is something we rely on for The following is an introduction to the a variety of everyday activities, from infrastructure of the internet, who owns it and Tsending emails, to streaming movies, to how it works. finding the locations of our favorite food trucks. In fact, according to the Pew Research Center, WHAT IS THE INTERNET AND WHERE while most Americans go online several times DID IT COME FROM? a day, a quarter of us are online essentially The concept of allowing computers to constantly. While many other technologies are communicate over a network originated just as saturated into our lives as the internet, shortly after the invention of the digital such as electricity, few are as invisible as the computer in the 1950s. In the late 1960s, internet. The average user of electricity cannot the defense department funded ARPANET, explain Ohm’s Law, just as the average user of which was a network that initially connected the internet cannot write computer programs, computers in the computer science but almost everyone is familiar with the massive departments of UCLA, UCSB, Stanford and investments in infrastructure that bring electricity the University of Utah. The network grew to our homes. Not only are we accustomed to to encompass dozens of universities and seeing overhead power lines and utility trucks government institutions in the United States. in our neighborhoods, millions of us spend our The physical network was comprised primarily vacations visiting places like the Hoover Dam of private phone line connections leased from learning about how electricity is generated. the telephone networks and managed by the Unfortunately, there are no similar attractions U.S. Department of Defense. The primary allowing tourists to gawk at and learn about the purpose of the network was to give computer massive underpinnings of the internet. science departments around the country direct

July/August 2019 3 27 How the internet connects A bit of terminology Router: A networking device that operates as a switch Sprint, CenturyLink (formerly Level 3) at the intersections of networks directing data traffic. (Tier 1 networks) Routers operate at every network connection, reading the destination IP address of each data packet coming 4 $ to them and then sending them along a network path. 2 3 Internet Cox Each router that a data packet encounters guides $ (Tier 2 network)

$ exchange point (Tier 2 network) it closer and closer to its destination. Routers come in a spectrum of sizes, from home routers with a

(Tier 2 network) Data $ couple connected computers and one outside internet centers

Local network connection to massive machines operating in internet $ Data (Tier 3 network) exchanges and data centers interfacing between the centers Data world’s largest networks.

$ $ $ 1 centers Internet users $ Modem: A device that converts data from one format Consumers, businesses, content Additional to another, allowing data to travel from a computer onto providers: e.g. Google.com, internet users Netflix.com, Amazon.com cable or phone lines, over radio waves or onto fiber optic lines and back again. The diagram above depicts a simplified version of the global internet. The Fiber optic cable: A cable made of strands of glass or gray lines represent connections between networks and users, and between plastic filament, which transmit data as pulses of light. networks themselves. In general, users and local network pay regional Each filament can carry data on multiple frequencies at networks for internet access and those regional networks pay global networks the same time and over long distances with little power, for access to the broader internet. making fiber optic cables generally the most efficient 1. Internet users typically pay their local or regional network (Tier 2 or 3) way of transmitting data. Fiber optic cables often have for a connection. immense capacities, allowing multiple networks to lease space on the same cable using different filaments or 2. Local and regional networks pay upstream networks for connectivity, providing frequencies to transmit data. the revenue for global backbone networks to build worldwide networks with connections on multiple continents. For example, Comcast (Tier 2) might pay a Host or server: Any computer connected to a network company such as CenturyLink (formerly Level 3) (Tier 1) so that its customers in the is a host. A computer that provides services to other United States can access websites or send email to people on other continents. computers on a network is a server. For example, a computer where a website is located (also referred 3. Internet exchange points, which are generally located in data centers, are the to as hosting a website) is a server, since it can be global hubs of internet connectivity, run by both nonprofits and commercial accessed by other computers viewing that website. companies, where networks can “peer” or connect and share traffic with one Websites can be hosted by servers as simple as another. These exchanges raise revenue by charging networks to connect, a single computer connected to a home network but the networks typically do not charge each other to connect because the providing access to a seldom-visited website, or they networks want to be connected to as many other networks as possible to can be hosted by arrays of computers filling football- achieve redundancy and reduce the number of backbone networks they have field-size data centers spread around the world, to pay. Exchange points with many networks tend to attract large content allowing millions of people to access sites such as providers and data centers to house them, since exchange points can give YouTube or Facebook. content providers easy access to many networks allowing for faster, and potentially cheaper, downloads of their content on each network. Data center: A building or other space dedicated to 4. In addition to wanting to be located at internet exchanges, large internet housing computer systems or users also seek out connections to Tier 1 backbone networks, giving them infrastructure. Data centers house the servers hosting fast and efficient connections around the world. the websites and analyzing the data used by consumers and businesses. Desirable data centers have access to reliable and affordable power, as well as access to Source: National Real Estate Advisors, LLC several large networks to access the internet.

access to the most powerful computers owned to mainframe computers. In the 1970s and by just a few universities. Despite its largely 1980s, additional networks were assembled academic intentions, the communication outside of military control, and by the 1980s power of the network was apparent by the it became clear that it would be a far more mid-1970s, when 75 percent of the traffic was efficient system if users could communicate email among users rather than commands sent with each other across all of the networks.

28 3 July/August 2019 In 1983, ARPANET switched to a universal Shipping network protocol system, which allowed the multiple existing networks to interlink. Container shipping network Over the following decades, these (e.g. Maersk) networks opened to the public and eventually for commercial use. In the process, they expanded, commercialized, Rail network changed ownership, modernized and (e.g. China Railway) multiplied — producing the worldwide network composed of tens of thousands Rail network of smaller and mostly private networks (e.g. CSX) collectively known as the internet. These smaller networks take various forms ranging Trucking co. Trucking co. from giant internet service providers such (e.g. U.S. Express) (e.g. China Logistics) as Comcast or Verizon, connecting millions of regional internet users; to backbone networks linking dispersed smaller networks Retailers, Retailers, together, such as CenturyLink (formerly manufacturers, businesses, consumers consumers Level 3), Cogent or Sprint; to content- delivery networks built by companies such as Google, Akamai or Amazon Web Services It may be helpful to think of the internet as it compares to the shipment of containers to strategically access other networks, around the world. Like a user accessing the internet, a retailer or manufacturer likely allowing for the fastest download times pays a single logistics company to ship a container of its products from a factory of their content. The complexity and overseas to its consumers in the United States. The container itself (like a packet private nature of these networks create a of data on the internet) will likely be handled by several different companies as it generally seamless but opaque online user moves, for example, from a railroad in Japan, to a global shipping company, and experience. By digging into the underlying finally to a trucking company in the United States that can deliver it to its destination. mechanics of how data travels across these Like a packet of data traveling on the internet, the container is labeled with networks on the web, we can begin to a final address and passed from company to company as it makes its way ever understand a bit more about the underlying closer to its destination. Also similar to the internet, the underlying infrastructure, infrastructure of the internet. of rails, roads and ports, is owned by a combination of corporations, investors and governments, while the operations are managed by global logistics companies, and HOW THE MODERN the complex network remains largely concealed from the ultimate customers. INTERNET WORKS: STRUCTURE The internet is primarily set up as series of internet Service Providers (ISP). ISPs Source: National Real Estate Advisors, LLC are the networks that provide users access to the broader internet. These networks ocean, likely on an intermediary backbone are typically owned and operated by for- network, to reach Japan. profit companies, with the large telecom Every internet network uses the same companies such as Sprint, Comcast language to communicate (internet Protocol, and Verizon operating some of the or IP), allowing data to be sent over the most extensive networks in the United internet regardless of the particular network States. Networks of any size are made it is traveling on. For this system to work, up of the same ingredients of routers, each computer connected to the internet is modems, fiber-optic lines, cell towers, and assigned a unique IP address. This address satellites and, from a user’s perspective, allows any connected computer to send data data travels unimpeded and efficiently to another one by sending out packets of data across all connected networks to reach labeled with its destination IP address. This its destination, regardless of who owns address allows all the routers that the data the network. For example, a person who packets encounter, on each network along subscribes to Comcast will not notice the way, to route the data closer and closer to any difference between sending an email its destination. When accessing a website, for to someone subscribing to Verizon, Cox example, you begin by clicking on a link or Communications or even NTT in Japan, typing in the web address. This address (e.g., even though the data must travel from www.google.com) is converted into Google’s the Comcast network onto an adjacent IP address and your request is sent to Google. network in the United States or across the When Google’s computer receives your

July/August 2019 3 29 Transmission examples

Although it is difficult to track exactly what path data travels on the internet due to the private and proprietary nature of the infrastructure owners, it is usually possible to see which networks are used, providing a sense of the structure of the internet. Below are a few examples of the journey that data traveled to fulfill some of the Philadelphia-based author’s recent website visits.

1. Comcast desktop visit to Amazon.com: 2. AT&T phone visit to Google.com:

3. Comcast desktop visit to thetimes.co.uk: 4. AT&T phone visit to nzherald.co.nz:

1. Visiting Amazon.com from a computer connected to the Comcast network on the East Coast resulted in connecting almost directly to Amazon servers in Ashburn, Va. This suggests that Amazon is also directly connected to Comcast. This scenario illustrates how large content provid- ers like Amazon locate their content around the world in many data centers connected to large networks in order to provide fast and reliable downloads to their users. 2. Visiting Google.com from an AT&T phone on the East Coast similarly resulted in connecting almost directly to Google servers. Google does not label its network as clearly as Amazon, so it is unclear where precisely the servers are located. Yet, Google likely pursues a similar strategy to Amazon of locating its content in many data centers as close to its consumers as possible. 3. A visit to thetimes.co.uk resulted in the data traveling across Comcast’s network, connecting to NTT’s network in New York and crossing the Atlantic Ocean to France. From there, the data continued traveling and connected to Amazon Web Services in a data center in Ireland where thetimes.co.uk is evidently hosted. 4. A visit to the New Zealand Herald from a phone worked similarly. From the phone, the data was sent via radio signal to the nearest cell station on a tower or nearby building. There it transferred from AT&T’s mobile network to its long-distance fiber optic network and travelled to Los Angeles. In Los Angeles, the data appears to have been routed to the Tata Communications Network, on which it traveled up to Seattle and then across the Pacific Ocean to New Zealand. In New Zealand, it transferred to Vodafone’s network and connected to theHerald’s servers. These examples of visiting smaller websites outside of the United States show how data must transfer across multiple networks owned by different corporations as it travels around the world. The two examples also suggest a different ownership structure of the servers in the data centers hosting the two publications. The Times appears to lease space on Amazon Web Services servers, while the Herald appears to control its own servers and data center space more directly.

Source: National Real Estate Advisors, LLC

30 3 July/August 2019 Infrastructure ownership: Southern Cross Cable

Graphic No. 4 on page 30 shows data traveling directly from the Seattle area to New Zealand on Tata Communications’ network. There are relatively few cables connecting New Zealand directly to the United States and none of them is owned by Tata Communications. Tata does, however, lease on the Southern Cross Cable (mapped to the left connecting the mainland United States, Hawaii, Fiji, Australia and New Zealand) owned by a joint venture between Spark New Zealand, SingTel and Verizon Business. Thus, it is likely that part of the New Zealand Herald’s internet and my phone plan’s subscription dollars pass from Vodafone and AT&T, respectively, on to Tata and again on to the cable operating company.

Source: National Real Estate Advisors, LLC request, it sends the data required to display Comcast or Cox Communications) are made its webpage back to your IP address and, up of local and regional cable and fiber optic therefore, your computer. This basic process connections. These are the networks that, is repeated for any task online, whether for a fee, consumers and businesses connect it is accessing websites, sending email, or to in order to access the internet. Revenue streaming music. The process will continue to generally flows upwards from consumers and work regardless of which networks connect businesses subscribing to the internet on local you and Google. The crucial component and regional networks to larger and more that changes if you switch networks is your connected networks. assigned IP address (and therefore the route Although networks own significant the data travels to get to you). For example, if parts of their infrastructure, they can often you access Google on your computer plugged more efficiently build networks by sharing into your home router, you are connected to infrastructure. Networks frequently lease your local ISP (e.g., Comcast), which is in turn bandwidth on fiber optic cables and satellites connected to the global internet. But, if you that give access to distant locations. They access the internet from your smart phone, may also lease space on redundant network your data will be sent via radio waves to a pathways that would be prohibitively cell tower connected to the carrier’s hardwired expensive to own creating resilience that network (e.g., AT&T) before being transferred networks and Internet users crave. Networks to another network and on to Google. may even lease local infrastructure in areas they don’t have expertise or to achieve THE BUSINESS OF NETWORKS economies of scale such as space in Internet Although all networks are made up of the exchanges or cell tower locations. Networks same general building blocks, they operate at even lease individual connection points on different scales and geographies. Backbone cell towers resulting in towers in prominent networks operate undersea cables and fiber locations holding equipment for Verizon, optic lines, which span continents connecting AT&T, T-Mobile and Sprint all at the same distant cities. Local and regional networks time. In addition to network operators, focus on connecting lots of homes and content providers may own and operate their businesses in dense networks, which in turn own data centers and servers, but they may connect to the backbone networks and the also lease space within multi-tenant data broader internet. A network’s market position centers or even on servers within data centers is largely determined by its size. Networks where small-scale players can gain access are conventionally broken down into three to dense network connections. Ownership tiers. Tier 1, or backbone networks (operated structures like these can create opportunities by companies such as CenturyLink (formerly for private investors, particularly in the most Level 3), Sprint or Tata Communications), are capital-intensive parts of networks like data global networks connecting local and regional centers and undersea cables. v networks around the world. These networks earn revenue by charging smaller networks Darob Malek-Madani is head of research and for access. Tier 2 and 3 networks (such as analysis with National Real Estate Advisors.

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